Robelle 2555 Super Mineral and Stain Erase for Swimming Pools, 1-Quart Helps prevent stains and discoloration from iron, copper, magnesium and other minerals This product is an excellent general purpose sequestrant which helps protect plumbing and pool walls from rust, stain and scale It should be used for all pool openings and closings and throughout the season as needed 1.5 ounces per 1,000 gallons